I've been trying to work through the challenges introduced in Wrath of the Lamb to unlock stuff in the Binding of Issac,but have noticed that I'm not winning the challenges after beating 'It Lives'. Do I have to also beat Sheol/Cathedral to be considered as having won the challenge, or am I encountering a glitch?
For each of the challenges, the boss that you need to beat to win the challenge is (from the wiki page):
So for the last two challenges, beating It Lives is not sufficient for completing the challenge.
In addition, in the most recent version challenge 9 cannot be completed according to the wiki.
More information about challenges is on the wiki page.